Deep submergence battery having gas bubble-electrolyte scrubbing vent cap



United States Patent 3 544 372 DEEP sUBMERGENcE BATTERY HAVING GASBUBBLE-ELECTROLYTE SCRUBBING VENT CAP Laurance Bridge, Levittown, WalterJ. Horner, Willow Grove, and Harold F. Thiel, Cornwell Heights, Pa.,assignors to ESB Incorporated, a corporation of Delaware Filed Sept. 26,1968, Ser. No. 762,893 Int. Cl. H01m 1/06 U.S. Cl. 136--6 4 ClaimsABSTRACT OF THE DISCLOSURE A pressure equalized deep Submergence batteryfor immersion in a salt or fresh water medium having an oilelectrolyteinterface beneath the cell cover is provided with a vent cap in thecover which scrubs drops of electrolyte from the discharge gas bubblesas they pass through the oil.

CROSS-REFERENCE TO RELATED APPLICATION This application is related tothe following other applications Ser. No. 762,792, filed Sept. 26, 1968and titled Pressure Equalized Deep Submergence Battery HavingOil-Electrolyte Interface Beneath the Cover, in which Earl L. Daniels,Jr. and Elmer M. Strohlein are the inventors.

The two applications, which are being filed concurrently, have beenassigned to a common assignee.

BACKGROUND OF THE INVENTION So they will not be crushed by the waterpressure at great depths, liquid electrolyte deep submergence batteriesfor use in seawater or fresh water must be so constructed that thepressure of the liquid inside the battery equals the pressure of theliquid outside. One way to achieve the pressure equalization is byproviding an opening in the cover of each cell in the battery, but thiscreates the problem that to prevent unwanted discharge of the batteryinto the water the elecrically conducive water must be kept away fromcontact with the electrolye inside each cell. To prevent this dischargefrom occurring and to prevent the water and electrolyte from mixing itis customary to have a layer of non-conductive oil or other liquidbetween the water and the electrolyte, which oil is contained in ahousing which must also be pressure equalized. The housing containingthe battery and oil is then immersed in water. The pressure equalizedhousing and the oil are the media through which the pressure of thewater outside the housing is transmitted to the electrolyte in theinterior of the battery, and the oil is also an electrical non-conductorwhich insulates the battery terminal posts and electrodes from dischargeagainst the water or housing. For constructions embodying these generalprinciples see US. Pats. Nos. 3,160,525 (issued to W. E. Hutchison etal. on Dec. 8, 1964) and 3,166,446 (issued to W. E. Hutchison on Jan.19, 1965).

As the pressure equalized battery is submerged the increasing pressurecauses the electrolyte to be compressed into a decreasing volume, and tobe sure that the battery always has sufiicient electrolyte even at greatdepths it has been common to provide an inverted collapsible bottle orreservoir containing excess electrolyte atop each cell of the battery;the collapsible bottle also serves as a pressure equalizing device. Theinterface of non-conductive oil and electrolyte is then in the bottle;see for instance the two Hutchison patents. The bottles have employedalves designed both to permit the flow of gases out of the cell and toprevent the flow of liquids into or out of the cell (see Jensens U.S.Pat. No. 3,208,884 and the Hutchison patent, respectively), and whilesatisfactory for their intended purposes these valves have not beendesigned to remove drops of electrolyte from the gas bubbles while thebubbles pass through the layer of oil. The escaping gas bubbles actuallycarry drops of electrolyte in their interiors, and excessive escape ofthese electrolyte drops can cause undesirable corrosion of both thesurrounding housing and other apparatus, can create a conductive paththrough the oil outside the battery case which can facilitate dischargeof the electrodes, and can reduce the quantity of electrolyte inside thecell and thereby limit the ability of the electrolye inside the cell andthereby limit the ability of the electrodes to charge and discharge asdesired. The gas bubbles are difficult to break up since they are in thelayer of oil as they pass through the gas valve or scrubbing device.

Other batteries not having an oil-electrolyte interface have beenprovided with vent caps designed to perform a variety of tasks. Somevent caps have been packed with a material intended to condense risingvapors; see U.S. Pat. No. 1,770,974 (issued to C. H. Everett on July 22,1930). Other vent caps have been filled with materials which absorbrising vapors; see U.S. Pat. No. 1,583,648 (issued to R. C. Benner OnMay 4, 1926). Still other vent caps contain materials which seek tochemically combine the rising gases, either by having the vent capfiller materials react chemically with the rising gases as is shown inU.S. Pat. No. 3,287,174 (issued to T. J. Hennigan et al. on Nov. 22,1966) or by functioning as catalysts; for vent caps containing catalyticmaterials, see U.S. Pats. Nos. 2,615,062 (issued to P. H. Craig on Oct.21, 1952), 2,687,448 and 2,687,449 (issued to H. M. Gulick et al. onAug. 24, 1954), 3,038,954 (issued to J. N. Pattison et al. on June 12,1962), and the Hennigan et al. patent listed above. These referenceslisted above are intended to be only illustrative of those showing ventplugs designed for purposes other than to scrub electrolyte drops fromgas bubbles passing through layers of oil.

SUMMARY OF THE INVENTION This invention is concerned with a deepSubmergence battery in which the battery is immersed in a non-conductiveoil and in which the oil has access to the interior of each cell tocreate an oil-electrolyte interface beneath the cover of each cell. Theinvention is applicable to single cell and multicell batteries, and isapplicable to a variety of electrochemical couples including, but notnecessarily limited to, lead-acid, silver-zinc, nickel-iron,nickel-cadmium, and silver-cadmium couples.

The cover of each cell is provided with an opening into which ascrubbing vent plug is fitted. The interior of this scrubbing vent plugis provided with a chamber, and holes near the bottom and near the topof the vent plug permit gas bubbles to pass into and out of the chamber.The tortuous path required for the gas bubbles to pass through the ventplug causes the bubbles to break, causing the drops of heavierelectrolyte to return downward to the electrolyte within the cell. Thetortuous path is made more difiicult and the vent cap is made moreeffective by filling the chamber with a scrubbing mate rial between orthrough which the gas bubbles must pass, and by providing the gas exitholes at the top of the side walls of the vent plug rather than in theupper surface of the plug.

BRIEF'DESCRIPTION OF THE DRAWINGS FIG. 1 shows a pressure-equalizedhousing containing a non-conductive oil in which a battery is submerged.The oil has access to the interior of each cell through the scrubbingvent plug and creates an oil-electrolyte interface beneath the cover ofeach cell. In the cover of each cell is the scrubbing vent plug withwhich this invention is concerned.

FIG. 2 shows an enlarged cross-section containing the vent plug of thisinvention fitted into an opening in the cell cover. The vent plug ofFIG. 2 is shown having its chamber partially filled with scrubbingmaterial, with the gas entrance holes in the lower surface of the gaschamber, and with the gas exit holes at the top of the side walls of thevent plug.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows in general terms aconstruction embodying the present invention. A housing equipped with apressure eqaulizing device 12 and a gas relief valve 14 contains abattery or cell 16 over the top of which is a cell cover 18. Theinterior of the housing is filled with an electrically non-conductiveoil or other liquid 20 which has access to the interior of the batterythrough an opening 22 in the cover. (Throughout the remainder of thisdiscussion and in the claims the word oil will be used to mean anyelectrically non-conductive liquid which floats on top of theelectrolyte and is compatible with the electrolyte, housing, and othercomponents of the combination. While there may be some such liquidswhich are technically not oils, the term oil will be used for sake ofsimplicity since the liquids commonly used for this purpose are oils.)The oil and electrolyte 24 form an interface beneath the cover, and theoil extends above the cell cover. Positive and negative terminal posts26 and 28 respectively lead from the electrodes within the battery casethrough the cover and are connected by cables 30 and 32 which extendthrough the housing walls. The drawing shows the cables 30 and 32 asbeing electrically insulated, but since the oil 20 serves as aninsulator this separate insulation surrounding the cables is not anessential requirement. The construction shown in the drawing may havesuch additional standard features as a removable cover for the housing,liquid drains, etc., but further refererence to them will be omtittedsince they are not germane to an understanding of the present invention.

The description thus far given is illustrative of the constructiondescribed in the cross-referenced related application. Much of thedetail given in that application can be summarized by saying that oneessential feature is that the pressure of the liquids inside the housing10 be made equal to the pressure of the liquids outside, and there arenumerous constructions which would meet this requirement. The housingitself might be made from a material such as rubber, metal, or a plasticwhich is sufliciently flexible so that the container deforms in responseto the outside pressure until the outside and inside pressures areequal. Alternatively the housing may be rigid and be provided with anexternally or internally projecting appendage which equalizes pressure,or a pressure equalizing diaphragm may be built into an otherwise rigidwall of the housing. The construction shown in FIG. 1 is to this extentonly schematic and is intended to include pressure eqalized housing ofall constructions. Arrangements to pressure equalize the housings areknown (see the two Hutchison patents cited in the background) and all ora portion of the battery case itself may be sufiiciently flexible to bea pressure equalizer (see the Orsinos U. S. Pat. No. 3,391,029).

Another frequently desirable but perhaps not always essential featureused in association with the housing is a gas relief valve. Again, thereare many different types of valves which could be used (see theHutchison, and Orsino patents as well as Jensens US. Pat. No. 3,208,-884) and for simplicity a schematic representation of a valve is shownat the top of the housing. It is desirable but not essential to have thegas relief valve at the highest point in the housing, and the top of thehousing shown in FIG. 1 is so constructed.

As was stated earlier, the oil 20 has access to the interior of thebattery or cell through an opening 22 in the cell cover 18. Fitted intothe opening by threads or otherwise is a scrubbing gas vent 34, shownbriefly in FIG. 1 and in greater detail in FIG. 2. (While oil will passthrough the gas vent 34 from the outside to the inside of the battery,it would be faster and frequently preferable to flood the interior ofthe housing with oil to a level above the cell cover before fitting thegas vent into the cover opening. In any event oil extends above the cellcover and surrounds the gas vent while the gas vent is in its operatingposition.) Portions of the vent plug may extend above and/or below theopening, or the plug may be entirely in the opening. The gas vent 34 hasan upper surface 36, a lower surface 38, and :side walls 40 whichdefined a chamber 42 within the vent plug. The gas vent has at least oneand preferably more gas entrance holes 44 in or near the bottom of thechamber and at least one and preferably more gas exit holes 46 near thetop of the chambers. Preferably the entrance holes 44 are in the lowersurface and the exit holes 46 are in the side walls, as shown in FIG. 2,but alternatively the entrance holes may be above the lower surface andthe exit holes may be in the upper surface, as shown in FIG. 3; thestated preferred constructions provie easy access by the gas bubbles tothe entrance holes and increase the tortuous path which the bubbles musttravel to get out of the vent chamber.

Preferably the chamber of the gas vent contains scrubbing material 48between or through which the gas bubbles must pass, as shown in FIG. 2.This material, which may be of many different constructions includingmatted or porous compositions or a collection of discrete particles,should be one which is chemically compatible with the electrolyte andoil, and materials such as plastics, some rubbers, ceramics, and othersare compatible with both acid and alkaline electrolytes and with mostoils. If the scrubbing material consists of a collection of discreteparticles, the particle may be of any desired configuration, withangular chips being preferable to spherical particles in most instancessince the sharp edges of the chips tend to break up the bubbles morereadily than do the spherical particles; particles which tend to packtogether without leaving open paths between themselves, such asrectangular particles, should be avoided. If there is to be a range ofsizes of particles in the chamberboth the maximum and minimum sizes aswell as the gradation within the range are variables which should bedetermined by experimentation for each dilferent application; theparticles should provide a tortuous path for the gas bubbles which willbreak up the bubbles and cause the electrolyte drops to return to theinterior of the battery case, and a gradation of particles which is toodense may restrict flow of gas bubbles. The particles should be of suchsize and configuration that they do not readily block or plug the gasentrance or exit holes, or both. The use of scrubbing material withinthe chamber of the gas vent is preferred but is not an essentialrequirement; a vent plug having no such scrubbing material, such as theone shown in FIG. 3, will work.

The size of the entrance and exit holes must also be carefullydetermined by experimentation, and should be large enough to permit thepassage of gas, small enough to break up some of the bubbles, and not solarge that the bubbles pass through with such ease that they are notbroken. The size and number of the entrance and exit holes are thusrelated to the size and number of bubbles generated during charge ordischarge, and these features are in turn dependent upon such factor asthe electrochemical couple involved, the rate of charge or discharge,the type and amount of oil being used, the pressure and temperature inwhich the bubbling occurs, the geometrical configuration of the battery,and perhaps others.

The deep submergence battery of the cross-referenced application differsfrom ours by having a gas bubble-electrolyte scrubbing means in thelayer of oil beneath the cover of each cell.

From the description given above the construction and operation of ourinvention should be clear.

We claim:

1. A pressure equalized deep submergence battery for immersion in awater medium comprising the combination of:

(a) a housing containing an electrically non-conductive oil, the housinghaving means for equalizing the pressure of the oil inside the housingwith the pressure of the water outside the housing; and

(b) a battery situated within the housing, the battery having a coverover each cell, each cover being provided with an opening which providesaccess by the oil to the interior of the cell, each cell having anoilelectrolyte interface beneath the cover; and,

(c) a scrubbing vent plug fitted into an opening in the cover of eachcell, each vent plug having an upper surface, a lower surface, and sidewalls which define a chamber within the vent plug, the vent plug havingat least one gas entrance hole near the bottom of the chamber and atleast one gas exit hole near the top of the chamber, the chambercontaining scrubbing material which is compatible with the oil and theelectrolyte.

2. The deep submergence battery of claim 1 in which the gas entrancehole is in the lower surface of the chamber.

3. The deep submergence battery of claim 1 in which the gas exit hole isin the side walls of the chamber.

4. The deep submergence battery of claim 2 in which the gas exit hole isin the side walls of the chamber.

References Cited UNITED STATES PATENTS 1,514,670 11/1924 Melchior 136178XR 2,930,828 3/1960 Herold 136-l70 XR 3,166,446 1/1965 Hutchison 136166XR DONALD L. WALTON, Primary Examiner US. Cl. X.R.

